Redirect to 404 page if css_id in URL is invalid

[yoomlam]

Resolves #13911

Description

Change to use user-friendly error page.

Acceptance Criteria

• Code compiles correctly

Testing Plan

1. Go to http://localhost:3000/queue/BVAAAAAAAABSHIRE/assign or http://localhost:3000/queue/BVAAAbBSHIRE

User Facing Changes

• Screenshots of UI changes added to PR & Original Issue

BEFORE	AFTER

[codeclimate]

Code Climate has analyzed commit f58f290 and detected 0 issues on this pull request.

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[ajspotts]

nice 🚀

[yoomlam]

Handled by

caseflow/app/controllers/application_controller.rb

Line 22 in 28d5b66

rescue_from ActiveRecord::RecordNotFound, with: :not_found

and

caseflow/app/controllers/application_base_controller.rb

Lines 45 to 49 in 9d9bc30

	def not_found
	respond_to do |format|
	format.html do
	render "errors/404", layout: "application", status: :not_found
	end

which loads https://github.com/department-of-veterans-affairs/caseflow/blob/7168968e0529c4957f04128cef19be0d32d66161/app/views/errors/404.html.erb
and causes the frontend to display

caseflow/client/app/errors/Error404.jsx

Lines 29 to 34 in 984e53f

	<StatusMessage title="Page not found">
	Oops! We can't find the correct page. If you need assistance,
	please visit the <Link to="/help">Caseflow Help Page</Link>.
	<p>If you continue to see this page, please contact
	the <a href={this.props.feedbackUrl}>Caseflow Help Desk</a>.</p>
	</StatusMessage>

More here.